Porsche 914-4 Weber Carb running rich, Weber Carb running rich on #4 only Options

[mturner7]

Hi Everyone,

My car is a 1974, 914-4 with a 2.0L (2056cc) engine. With Weber IDF 44's.
My #4 cylinder is running really rich. All the others are fine.

The Question is: What in the carburetor could most likely cause the plug to foul (Running very rich) like in my case? I've tried to adj the air/fuel mixture screw still no change.

This is what I've done so far:

0) Did a compression check on all cylinders. All ok. (95-100psi) 
1) Changed the plugs.
2) Changed the Cap and Rotor.
3) Changed the plug wires.
4) Verified all the jets are the same.
5) Set the Air flow on each carb, sync'd them
6) I cleaned all the jets with the carb in the car, ran and idled much better.
7) Verified Spark to that Cyl, got a hell of a shock out of it.
8) I'm running Elec-Ignition, Flamethrower Coil, 60,000volts.

After doing all this, the #4 plug still fouls after only about 20 to 30 miles. It has to be the carburetor.

I just pulled the carburetor. Thanks for the help.

[Superhawk996]

Those carbs have been modified

1st thing I would suspect is blockage within the thin brass tubes that lead to the calibrated brass bushings that supply air to the idle jet

IDF’s run on the idle circuit when cruising under light load.

I would also measure all the jets and make sure someone hasn’t drilled out #4 larger than what it is stamped as.